Clemens, in U.S. Pat. No. 3,842,194, incorporated herein by reference, has disclosed a system for recording and playback of information including audio, video and color information capacitively. The high density information record has signal information in the form of a surface relief pattern in an information track, e.g., a spiral groove, on the surface of a disc. The disc is made conductive with a metal layer which acts as a first electrode of a capacitor, and which is coated with a dielectric layer and played back by means of a stylus electrode, which is the second electrode of the capacitor. Matthies, in U.S. Pat. No. 3,833,408 also herein incorporated by reference, discloses a methyl alkyl siloxane lubricant useful for the disc. The lubricant reduces friction between the disc and the stylus and thus reduces stylus wear.
Improvements made to the system since its early development include making a disc from a conductive plastic material made by adding conductive carbon black particles to a PVC matrix. This eliminated the need for separate metal and dielectric layers on the disc. The lubricant has also been improved by selecting a fractionated, purified methyl alkyl siloxane material. This has been disclosed by Wang et al in copending application Ser. No. 065,065, filed Aug. 9, 1979 now U.S. Pat. No. 4,275,101. This material has the formula ##STR2## wherein R.sub.1 and R.sub.2 are alkyl groups of 4-20 carbon atoms, x is an integer of 2-4 and y is an integer of 0-2 and wherein the sum of x and y is 4 or less. The improved lubricant has better long term stability and improved first play performance.
One of the problems of the above described discs has been a sensitivity to degradation in the presence of water. When a carbon-loaded PVC disc is stored in or cycled through a warm, wet environment, a thin layer of solids, including organic and inorganic salts, forms on the surface of the disc, probably caused by various incompatible additives and products of degradation bleeding to the surface. When droplets of water deposit on the surface, these salts dissolve in the droplet. When the water evaporates, a nodule of salt is left behind that interferes with playback. When the stylus reaches such a deposit, it must ride over it whereupon the playback is interrupted, resulting in a loss of signal. In extreme cases, the stylus locks in the information track or skips a number of information tracks. These phenomena are called carrier distress which is measured as seconds of playback time during which signal information is lost. This problem has been somewhat alleviated by cleaning the discs after molding which removes the materials on the surface. However, with time, additional materials bleed to the surface or are formed on the surface due to oxidation reactions and the like, and carrier distress recurs, particularly after several cycles of water deposition and drying on the disc surface.